Colloidal crystal arrays are valued for their optical properties, connected pore network, and ease of assembly. In various applications opals have been used as templates to produce material utilized in optoelectronic devices, sensing applications and energy storage in order to take advantage of the interconnected three-dimensional structure and/or strong optical properties. Generally, the opal platform has been limited to silica, poly(methyl methacrylate) or polystyrene colloids. These opals can be converted to other materials through templating processes, where materials are grown around the opal. When necessary, the process step is followed by opal removal. Various devices and applications benefit from the use of high-surface area structures that are derived from opal templates. These include but are not limited to solar cell anodes and the like.
Incorporation of carbon such as carbon black into polymer opals has resulted in brilliant colors due to suppression of back reflected scattered light. While carbon framework inverse opals have been fabricated, carbon opals have only been realized through chemical vapor deposition (CVD) on a sacrificial, mesoporous silica opal. CVD and related etching processes are complex and time consuming. While this process does create an opal structure, it would be desirable to provide a process that would accomplish self-assembly of carbon colloids in a manner that would eliminate the need for CVD and etching processes. Due to the high thermal stability of carbon (greater than 1000° C. in inert environment), a self-assembled carbon opal would be highly desirable for high-temperature inversion as well as for their inherent properties. High quality colloidal crystals require colloids that are monodispersed (defined herein as having a size variation less than about 5%) and that form a stable suspension. The production of such materials from carbon has been problematic.
It would be desirable to produce high quality colloids, particularly those that would be thermally stable and could permit development of additional fabrication techniques. It is also desirable to provide opals which could be removed via orthogonal processes relative to other materials, and thus provide the opportunity to template materials which otherwise cannot be templated. An orthogonal template material is one that can be removed in a manner or process that does not negatively interact with the inverse structure. It would also be desirable to produce high-surface area structures based on an opal platform as well as to produce materials based on the same.